My 180 houses

1 Pink Streak Wrasse aka 4line
1 Red Corris
1 Purple Belly
1 Xmas wrasse

I have no problems but I have a 180g tank, they all tend to stick to their own zones. The Red Corris which will be the largest as a adult spends the entire day picking at the sand. The others cruise the rock work looking for pods.

Id recomment sticking with a smaller species if you do add another. A six, eight or 4 line would probably work out well.